This invention relates to foam blowing agent blends of (a) n- and/or i-pentane with (b) 1-chloro-1,1-difluoroethane ("142b") or 2-chloro-1,1,1,2-tetrafluoroethane ("124"), more particularly to blends containing about 10-90 weight % of each of (a) and (b) and to polyol premixes and polyurethane foam compositions containing such blends.
Until now, the leading polyurethane foam blowing agent has been 1,1-dichloro-1-fluoroethane ("141b"), in order to meet the market place requirements for energy, fire performance and cost. At the same time, however, 141b has a high ozone depletion potential ("ODP") of about 0.1. Thus, many foam manufacturers are now investigating cyclopentane as a leading alternative candidate to replace 141b. Cyclopentane has zero ODP, but also has property shortcomings in terms of fire performance and aged k-factor performance (and thus, thermal insulating properties).
It would therefore be useful to provide the industry with a foam blowing agent which overcomes the deficiencies of both 141b and cyclopentane in terms of properties such as ODP, fire performance, k-factor aging and the like.
While articles have been written on the subject of blended blowing agents, such as Research Disclosure 40137 (September 1997) on Hydrochlorofluorocarbon-hydrocarbon Mixtures, the actual data presented is that of blends containing the industry standard, 141b.